Electrical system



Oct. 28 R. E. HELLMUND 1513'242 ELECTRICAL SYSTEM Filed June 18 1919 2 Sheets-Sheet. l

' ITNESSES: I I I INVENTOR M fiuda/fEfi/eflmuna W ATT ORNEY Oct. 28. 1924.

' R. E. HELLMUND ELECTRICAL SYSTEM Filed June 18. 1919 2 Sheets-Sheet 2 77-a//e Tro/lr I INVENTOR lPua o/fi //e llmuna' round /$T ESSES 2 I Patented Oct. 28, 1924.

UNITED STATES RUDOLF E. HELLMUND, OF STNISSVALE, PENNSYLVANZA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING GG'MPAITY, A CORPORATION OF PENNSYL- VANIA.

ELECTRICAL SYSTEM.

Application filed June 18, 1919.

7'0 oil-Z tU/lOHL- it may concern:

Be it known that I, RUnoLr E. HELL- MUND, a citizen of the German Empire, and a resident of Swissva'le, .in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Elect ical Systems, of which the following is a specification.

My invention relates to electrical systems and particularly to constant-voltage systems for train-lighting purposes and the like.

One object of my invention is to provide arelatively simple and reliable system of the above-indicated character which eliminates the auxiliary brushes and the special pole construction that have been employed in some train-lighting systems of the prior art.

Viewed from a different angle, the object of my invention is to provide, in conjunction with a motor-generator set, or the equivalent, an auxiliary armature winding that is connected to influence the field windings of the motor-generator set different y upon a variation of supply-circuit voltage, to change the voltage ratio of the motor and generator armatures; or, in other words, to maintain a substantially constant genera-tor voltage.

Other specific objects of my present invention will become evident from the following detailed description, talren in. conjunction with the accompanying drawings, wherein Fig. "i is a diagrammatic view of the essential. circuits of an electrical system embodying the invention; and Fig. 2 to Fig. inclusive, are similar diagrammatic views of various modifications of the inveir tion.

Referring to Fig. l the system shown comprises suitable supply-circuit conductors Trolley and Ground for s pplying energy to a motor-generator set having a driving armature winding A1, a generating armature winding A2 and auxiliary armature winding l, a-ll mounted upon the same operating shaft 2. The armature windings Al and A2 are providedwvith series-related field windings F1 and F2, respectively, and with shunt-related field windings F3 and F4, respectively.

The auxiliary armature- Serial No. 305,105.

winding 1 is provided with a series-related field winding 3 and with a field winding 4 that is excited from the generating armature A2.

One or more banks of incandescent lamps 5 are connected across the terminals of the generating armature A2 and, in addition, a storage battery 6 floats across the generating-armature distribution circuit, in accordance with familiar principles.

As indicated by the plus signs, the field windings F1 and F3 for the motor armature winding A1 are cumulative, or assist each other, and the same statement holds true with respect to the field windings F2 and F4 for the generating-armature wind ing A2. The auxiliary armature winding 1 is connected in opposing series relation with the field winding F3, as indicated by the minus sign; or, in other words, serves to decrease thevoltage that is impressed upon the field winding F3 from the supply circuit. A resistor R is also connected in circuit with the field winding F3, for purposes to be described.

Assuming that the line voltage suddenly decreases, the voltage across the motor armature-winding A1 also decreases, while the voltage across the generating armature A2 remains practically constant because of the parallel-connected battery 6. Even without such battery, the tendency of the latter voltage will be to remain constant, primarily because the speed of the motor-generator set is prevented from changing instantaneously bv the inertia of the rotating parts and, further, because the damping efiect and the high self-induction of the shunt field F4 prevents the exciting field flux from dropping off quickly.

The reason why the voltage of the armature can rapidly compensate for the changed line voltage is partly because of the use of the resistance R, which imparts asmaller time elements to the circuit lot the field winding F3, thus permitting the current to quickly "follow all voltage changes. Furthermore, the auxiliary armature 1 assists in the proper readjustment. This action may be demonstrated best by an example.

Assume, for instance, that the armature A2 volts.

'GXCltGCl by a con a voltageiot 133.3 volts remains for thefield is to furnish a constant voltage of 200 volts,viously shown, however, the voltage for the while the line voltage suddenly drops from 600 to 400 volts. The armature A1 thus has to change its voltage from 400 to 200 It the auxiliary armature l. has an electro-motive tone of 66.7 volts, while the line voltage is 600 volts, (40066.7) :3333. volts are impressed upon the field winding F3 and the resistor R. "VVhenthe line volt-' age drops to' lOO volts, the voltage of the auxiliary armature 1 remains 66.7 volts, neg lecting, for the present, the eitect of the'field winding 3, because the field winding 4- is stant voltage. Thus, only F3 and the resistorR. In-other words, the field eXClt3tiO11-f0l;tl18 motor armature A1 has dropped from 333.3 to 133.3, while thearmaturevoltage has changed from 400 to' 200. The greaterrelative voltage drop in the fieldv winding: serves tomaintain con-*1 stant speed in spiteofthe lower armature. voltage; V Consequently, the voltage of the generating armature AQ will-remain c0n-- stanuas desirable. 1 ii hilethe-resistor R- tends to impart a small time element to-thecircuit' of the" field winding F 3, there is, nevertheless, suificie'nt self-induction in the field winding to cause a certain lag of the currentcha1'1ges"behind the voltage variations. Such lag may further be reduced by the acti-onot the field Winding 3, "assho'wn by the following six aniples. .7

Again assume conditions as before, except that with- 600 volts line "voltage theaux iliary armature furnishes 100 volts. "The field windings 3 and4 are'so proportioned that the Winding 4: induces a field 'fiux cor responding to 50 *volts in the armature '1 7 while the winding 3, also induces'a voltage of 50 volts in that armature, resulting; as =as* sumed, in; a total of NO-volts. L the line' voltage again drops [0400 volts", both field'f fluxes will at "first remain unchanged, the} self-induction preventing the current in "the field WindingB from changing"immediately. Thus (200.100)=10O volts are-impressed upon the field winding F3 and the resistor R. Subsequently, ings F3 and 3 diminishes on account o fthe appreciably lowered voltage; Assuming that such current drops toof its'original value, u

by the field winding 3, giving a; total :of 266.7 volts in the auxiliaryarmaturef1',':thus leaving (200 667) 1333 volts for'the fieldwindingF3 andthe re-' sistor :Therefore; for s iiiiied' CQDflh" ti-ons', afieldvc ltage drop irom .131533 volts occnrs,1which is larger th'anthe drop in" armature voltage, as is desirable. "As pre volts are induced the current in thewind-f from 1 mg the field w1nd1ng3 1n series. relat on w th my uxlllary armature winding 1,111 lieu of field creas value as low as 100 volt materially assists in reducing the field current will be seen, therefore, that I provide,

not only an arrangement that is suitably operative to maintain stabil zed conditions,

but also means to sired changes in The action of r quickly effecting the... demachine conditions. the field windings F1 and F2 maybe arranged by proper'choice of saturation, etc., to give the desired compound effect with changingl wind flashing tendency otthe machines.

The converse e rapid increase of the lstrength of the field winding F3, occurs increase of Trolley v oad current; these field in reducing the ing's, furthermore, assist.

tfect, including 'a relatively in the event ofa sudden oltage, as will be understood without further exposition, whereby again the speed and n'iotor-generator setstantially constant.

delivered'voltage of the. may lye-maintained sub- Rcfe'rring to 2, the armatures A1 and A2 andfthe associated field windingsFl and while 'the field w series relation with the field winding 3' for F2 are connected as already described,

1nd1ng F3 is connected in the auxiliaryarmature-winding land with the field winding F4 for the generating {UT-1 mature A The auxiliary armature-winding" 1 is connected from a point windings F the field windings 2 across "the supply I circuit. 7

intermediate the field land F2to a point intermediate,

3and Ft. The auxiliar armature winding 1 is fthus'connected across each 7 to add to the voltage of the field winding and to subtr'a winding F4,

of the other machines and arranged ct fi'omthe voltage of the field ing plus and minus signs.

decreases,

field 'wher ture cieas wind wind auxil quently, it 'i s ieviden readi the a suming that the line voltage suddenly for example, the current in the windings and F3 likewise diminishes,

eby the voltage of the auxiliaryarmawinding 1Iis reducedto efiect an ine iii the currenttraversing the field ingF4. Thus, the current in the field ing F3 for the motor for the generating 2 is increased, by reason iary a as winding thein otlor armature A l coin- 'orfabsorbs' all var1at]ons. n,

i i i p -irsi tie ae r earring .t Fig. 3','jthe' system differs that shown in 2 only connectas indicated by'the correspond armature windin g if being connected in series relation with the field winding Again, the arrangement of parts is such that the voltage of the auxiliary armature winding 1 adds to the volt age impressed upon the field winding F3 from the supply circuit and subtracts from the voltage impressed upon the field winding F4. Furthermore, it is assumed that the motor is less magnetically saturated than the generator and that, under normal voltage conditions, the field winding F3 carries slightly more current than the field winding F4, the auxiliary armature winding 1 and its field winding 3 being traversed by the difference in such currents.

In the event of a sudden decrease of line voltage, therefore, the flux of the field win ling F3 decreases more rapidly than that of the field winding F4, which results in a more rapid decrease of current and voltage in the auxiliary machine than in the voltage of the motor armature winding A1. Consequently, the auxiliary machine inherently eflects different variations in the effects of the field windings F3 and F4. for the motor and the generator, respectively, to produce the desired substantially constant voltage in the generating armature A2, as previously described. I

In Fig.4, an auxiliary armature winding upon the generating machine is substituted for the previously illustrated separate auxiliary machine. The generating armature A2 is thus employed for supplying energy directly to the load of incandescent lamps 5, while the auxiliary armature winding 1, which is wound upon the same core as the armature A2, is connected in series relation with a field winding F4 for the combined generating machine and the field winding F3 for the motor armature winding A1. The voltage of the auxiliary an mature winding 1 is adapted to oppose that of the motor-armature winding A1, so that the voltage impressed upon the field windings F3 and F4 equals the difiierencebetween the voltages of those two armature windings. Under normal voltage conditions, the electromotive force of the auxiliary armature winding 1 is slightly lower than that of the motor armature winding A1, which re quires that the field winding F4 difierential, with respect to the field wind F2 for the generator, as indicated by the responding plus and minus signs, whereas the field winding F3 should act cumulatively with respect to the associated field winding F1, as also indicated by the accompanying plus signs.

Upon a. sudden decrease of line voltage, the voltage of the motor-armature winding A1 diminishes at a more rapid rate than those of the armature windings 1 and A2. for previously specified reasons, whereby the resultant voltage impressed across the field should be p windings F3 and F4 decreases at a relatively rapid rate and may even reverse. Such action tends to materially increase the field flux of the generating machine and to de crease the field flux of the d 'iving machine, as is desirable for the purpose of increasing the speed of the motor-generator set and maintaining a substantially constant deliv oltage thereol.

In Fig. 5, the difierential voltage effect of the armature windings A1 and 1 is adapted to influence only the field winding F3, the field winding F4, in the present case, being connected directly across the terminals of the generating armature winding A2. The operation of the system of Fig. will be evident from its analogy to that of the system shown in Fig. 4, and it will be appreciated that, if desired, the differential voltage efiect in question may be arranged to influence the field winding F4 only.

The two systems now to be described dispense with the battery 6. Referring to Fig. 6, he motor armature winding A1 and the generator armature winding A2 are provided with shunt-related field windings F1 and F2, which are directly connected by a variable resistor 9. lhe relative effects of the resistor upon the field windings F1 and F2 varied by means of a relay derice 8, which is differentially energized in rcordance with the voltage of the generatnig armature A2 and of the delivered voltage of an auxiliary motor-generator set- 10.

The auxiliary motor-generator set 10 rises a driving armature winding 11 that is connected across the supply circuit and a generating armature winding 12 which is mechanically connected to the driving armature 11 through the agency of a shaft 13, for e "ample. A plurality of field windings 14 and 15 are provided for the driving armature winding 11, being respectively connected across that armature winding and across the terminals of the motor armature winding A1. In case the auxiliary motor of the motor-generator set 10 may be maintained magnetically unsaturated throughout its working range, then the shunt field winding 14 alone will be sufficient to render the motor-generator-set speed independent of the line voltage. However, if a small degree of saturation can not be avoided, then the second field winding 15. connected as shown, may be utilized.

A series field winding 16 for the generating armature winding 12 is connected through an actuating coil 21 for the relay (ilEYiCE- 8, the terminals ot'tbe armature winding 12.

The relay device 8 comprises. essentially, a plurality of alined magnetizable core members 20 and 22, which are respectively provided with actuating coils 21 and 23 acting difierentially and respectively energized in accordance with the voltage of the auxiliary generating armature 12 and of thei main generating armature A2. The switch :arm- 24: makes contact with various taps 0i": theresistorS in accordance with the movement of therelay device 8, the switch arm 24' being connected through a suitable flexible conductor between the resistor 9 and a. point intermediate the armature windings A1 and A2.

Upon a sudden decrease of line voltage, the voltage of J the main motor armature windinglAl'diminishes more rapidly than the" supply-circuit voltage, as previously pointedout,-whereby the resultant field flux emitted: by the field windings 14 and 15 likewise decreases=more rapidly than the line tially eliminated;

voltage thus maintaining the speed of the auxiliary motor-generator set 10 substan- In Figw7, the driving armature winding 11 for'tlieauxiliary lllOtOP-gBIlGIEltOISQt 10 is connected acoss thesubstantially constantvoltageainature winding A2, whereby such slight variations in speed asmay occur in the auxiliary riiotor generatorset 10, when connected as shown in Fig. 6, are substan- The-field windings F1 and F2 are con- .nectedoin series relation with the armature windings A1 and A2, and the'variable'resistor 9 is connectedin parallel relation to the field'winding F2." In the present case, a relay 8 has its actuating coils 21 and 23 connected as already 'describediin connection with F-igittiythe relayibe ing" provided with movable 'contacttplate which is adapted to engage various numbers of control fingers 31 that aresconnected to the resistor 9,"as the relay ClfiVlCGlZlflVGlS up and-down in accord- 5 ance withithe relation of the voltage of the armature-Winding. A2to that'of the armature winidingi 12.41 11 this case also, therefore, theslightvariations in'the voltage of" theinain generator armature A2 are utilized to so vary'the active ci'cuit value of theresistor 9r as to compensate for the supplycircuit-voltage fluctuations by properly varying the voltage impressed upon the field winding F2 for the armature winding-A2.

It should be understood that all of the generator armature winding.

an unequal re to' efiect an unequal illustrated field windingsfor the various armature windings are not necessary in" ever case and in articular the field winda a P ings F1 and FZ'may, if desired, be omitted in those cz'ises where the associated field windings F3 and F4 are provided. It is further" possible to add to'the various sys temsmeans for speediiigup the: desired changes in theun achine conditions, such V the resistor R and the fieldwinding 3 shown in Fig. 1. Other variations in the particular field-winding connections to be employed may also be made without departing trom the spirit and scope of my nvention. Y

I desire, therefore, that only such limitations shall be imposed as are indicated in the ap pended claims. 7

I claim as my invention: I V l. The combination with p a supply circuit, a motor armature winding and a gen of an a'uxiliaryarmature windingcoiinected to influence the excitation of the motor and eratorjari'nature' winding driven thereby;

the generator arniat 'ire differently upon a variation of su a'ply-circuitvoltage.

ill)

2. The COlllblllfitlOIiWllZh a mowiarniature winding and a generator armature winding driven thereby, of a plurality of field windings for exciting said arnia ture windings, and an auxiliaryarmature winding rotatable with said'inotor armature and connected to influence said field'wind ings differently under predetermii iedoperating conditions and change the normal volt- I generator" age ratio of said motor to said armature winding; l

3. The coinbination with a supply circuit, a motor armature winding and a generator armature winding driven thereby, alityotfield windings for exciting said armature windings, and an auxiliary armature winding connected to influence said; field windings difitere itly upon a: variation in supply-circuit voltage and change the normal voltage ratio of said motor to said 4. The combination with a motor armature winding and a generator armature of a plu-' winding driven thereby, of a plurality of field windings inherently adapted to effect v V duction of exciting flux for said armature fwindiiigsunder predetermined operating conditions, and nieansfor accentuatingsuch unequal reduction. a. Thefcoinbination with asi pply circuit.

a motor; armature windingand a. generator armature winding driven thereby, of a P1111.

ralityof field windings inherentlyadapted flux for said armature windings upon a variation of supply-circuit voltage, and dynamo-electric means for accentuating such unequal reduction. I r

6. The 'coinbination with a supply circuit, a motor armature winding and a generator reduction of exciting upon producing an impulse acting to exaggerate such unequal reduction;

In testimony whereof, I have hereunto 10 subscribed my name this 6th day of June, 1919.

RUDOLF E. HELLMUND. 

